The New Nature Page 9
Native bush flies (Musca vetustissima) also like human dung, and flock to our faces as well to lap up proteins secreted in fluids by our eyes, noses and mouths. François Pelsaert found them troublesome in Western Australia back in 1629: ‘We also found such multitudes of flies here, which perched on our mouths and crept into our eyes, that we could not keep them off our persons.’ Aborigines were much bothered. ‘Their Eye-lids are always half closed, to keep the Flies out of their Eyes; they being so troublesome here’, noted William Dampier in 1688. Most bush flies back then would have bred in human do, which is damper and more copious than kangaroo pellets. An average human stool yields 150 flies. Bush flies must have done well when the megafauna roamed, and they do even better today. These days they breed up in millions in cowpats. Cattle produce a dozen pats a day, each of which can generate 1500 flies. The CSIRO’s John Matthiessen and Lynne Hayles note that cowpats range from ‘fine and fluid in early winter to more particulate and sloppy in early spring, then coarse and stiff in early summer to the finer textured and less thick dung later in summer’. The number and size of flies emerging reflects the quality of product. Lush green pastures produce the best medium.
When we flush our toilets or put out our rubbish bins we seldom give much thought to where our wastes go. As it happens, our sewage really counts. It influences the survival of ducks on desert billabongs, rare plants on islands, waders in Siberia and rainforest trees near towns. People and nature are more entwined than we might think. We are part of a vast foodweb that links us to sharks, snakes, frogs and who knows what else.
1 Melbourne’s other sewage plant – the Eastern Treatment Plant, opened in 1975 – feeds effluent into Bass Strait near Cape Schanck.
2 These numbers include coprophilous Aphodiinae as well as Scarabaeinae.
‘If I am doing field work, the first place I check out is the local dump.’
Wes Mannion, reptile expert at the Australia Zoo
In our cities skyscrapers soar like mountains above the concrete canyons. The valley floors support a simple detritus community of sparrows, pigeons, gulls and roaches gorging on waste and decay. Perched atop this metropolitan food chain is that sleek native predator the peregrine falcon. In Melbourne, Sydney and Brisbane these raptors drift over the ranges before swooping down on hapless pigeons in parks. In Melbourne I’ve watched one glide towards me from the Optus tower where they nest. Many of the French fries doled out to tatty pigeons end up by fattening these fierce birds of prey. The most anyone gets to know about them is when a few feathers flutter down from an eyrie on a high ledge.
I remember a time when peregrines were said to be dying out (from DDT). Instead they have invaded our cities. They wander through Perth, Canberra, Townsville, and the Gold Coast, and overseas they occupy New York, Los Angeles, Montreal, Munich, and many other centres. The world’s ultimate speed-masters – clocked at 350 kilometres an hour – they serve as symbols of wildness and wide open spaces. To me they signify other things: life’s flexibility; nature’s urgent wish to fit in.
Traditionally peregrines nested on cliffs, but their repertoire today includes bridges, silos, dam walls, mine shafts and quarries. A pair near Canberra weren’t deterred when 1800 kilograms of high explosive blew off part of the quarry wall beside them. Nankeen kestrels nest on buildings too; they hunt grasshoppers and mice in railway yards and industrial zones. In London 200 common kestrels (a different bird) nest in the greater city on steeples, cranes, pylons, factories and towers.
Landscapes today are shaped by people. We do more than weather and tectonics to mould the land. Our structures – buildings, dams, roads, quarries – and the clearings we make exert a major influence on wildlife. They complicate the landscape, bringing resources together in useful combinations: land and water, food and shelter, clearing and thicket. Buildings and communication structures add height, which is important for birds. In every landscape time lowers and we raise. Animals are often adept at assessing our structures and using them for their own needs.
Telegraph poles and wires now serve as streamlined trees with customised perches. A bird on a wire has commanding views of both prey and foes. Mice and lizards on the ground know to stay alert where trees loom, but don’t see the wires in the sky or those waiting eyes. Kestrels, kingfishers and butcherbirds like hunting from wires. Swallows are so keen on wires you seldom see them in trees any more. By commuting between wires and nests on walls they can live out their lives without ever touching a natural surface.
The poles holding up the wires make useful sites for nesting. Crows and ravens find the carrion served up on roads below conveniently located for their needy broods. Wedge-tailed eagles often nest on poles. For nearly a hundred years Western Australia was linked to the east coast by a telegraph line across the Nullarbor. Taller than desert trees, the supporting poles afforded commanding views over the plains. When satellites and optical fibres made the telegraph redundant, the line was removed. Birds Australia complained, wanting every fifth pole retained for birds of prey. Their representative Hugo Phillipps pointed out that ‘simple-minded, aesthetic perceptions of environmental values can be at odds with ecological realities’. The birds using the poles even played a valuable role by harvesting rabbits.
The phone boxes on poles get taken over by feathertail gliders. These plastic homes are ‘warm, dry and with a tight entrance hole that excludes most of the competition!’, notes feathertail expert Simon Ward. Biologists studying these tiny creatures often tag along behind Telstra technicians. Small bats also use terminal boxes, as well as nestling under the metal caps on the tops of poles.
Telegraph wires usually follow roads, and roads have their own ecological values. Although they are death traps for many, including basking reptiles, the carrion so created feeds birds of prey, which patrol roads just as they patrol rivers. In the Outback rain running off roads sustains a lush road-verge flora, often characterised by button grass (Dactyloctenium radulans), rat-tails (Dysphania kalpari) and wild tomatoes (Solanum). Biologists near Alice Springs showed that roadside mulga trees (Acacia aneura) have more water in their leaves than trees further away, which helps explains why mistletoes fare well along roads – they like lush trees. Frogs breed in roadside ditches and birds like to nest in roadside trees.
Dirt tracks through bushland are patrolled by tiny bats at night, and pardalotes – tiny birds – bore nest holes into sandy cuttings. (They also nest in loads of sand dumped in cities for construction work.) Meat ants (Iridomyrmex) love to nest in and patrol old dirt roads. On Christmas Island there is a rare bat that likes to forage along old tracks cut through the rainforest. The isle was densely wooded in the 1880s, and might be better for bats in the fragmented state it’s in today.
Where roads cross creeks, culverts offer their own advantages for wildlife. Along some country roads every culvert is marked out by swirls of martins. These days fairy martins, like swallows, usually nest on bridges and buildings, up to 700 nests to a bridge. Martins will dive into culverts even while raging floodwaters threaten their homes. Culverts are popular because creeks supply water for drinking and mud for nesting, and attract the flying insects martins eat. Martins also need the shelter culverts provide, because rain softens their nests. Traditional martin nest sites – caverns, cliffs and large leaning trees – are much scarcer and often poorly located. African little swifts are also culvert converts. I’ve seen a hundred wheeling around one crossing. Old martin nests, which are dark inside and shaped vaguely like bottles, are taken over by tiny bats. Eleven bat species, some of them rare, are known to use these old nests under culverts. Human architecture helps martins, and martin architecture helps bats.
Culverts also accommodate bats directly. In central Queensland Lindsay Agnew showed me how to survey bridges by poking wire into drainage holes and expansion joints. He often finds eastern cave bats in these places: they like the high humidity. A culvert near my house has tiny bentwing bats clustered in its concrete holes. Lindsay also sh
owed me geckoes in culverts, inside concrete cracks. Mud-daubing wasps like culverts as well, for the same reasons martins do: mud, shelter and insect prey.
Bats are also fond of our houses and mines. Large, complex mines often carry more bats even when caves await nearby. An old Chinese gold mine in the Northern Territory houses the world’s largest colony of rare ghost bats. In one north Queensland mine all the leafnosed bats are orange, not fawn, because ammonia in the mine has apparently bleached their fur. Mines and buildings offer certain advantages over caves and tree holes. Single-draft mines hold humidity better than holey caves where draughts blow through. Humidity matters because bats lose moisture from their naked wings. Mines also allow bats to invade regions where caves don’t form. They have proved a boon to virtually all cave-dwelling species.
The bats inside houses are mostly forest bats that otherwise use hollow trees. ‘There’s a house in Logan where just about the whole wall fell off because there was so much bat shit in there,’ bat expert Les Hall told me. ‘The woman who owned the house was quite happy about the bats as long as they didn’t fly inside the house. When she went to bed, she used to put up an umbrella to keep them out of her hair.’ Les tells good bat stories. ‘I remember a bloke showing me part of his ceiling that collapsed. It happened in the dining room, which was covered in bat shit. The ceiling fell down, fortunately not while they were eating.’
Other tenants in houses include carpet pythons, wasps, swallows and brushtail possums. In a box under my house a possum lies asleep right now. Fence skinks (Cryptoblepharus virgatus) sometimes venture onto my roof – they like flat surfaces on which small insects land. Melbourne’s marbled geckoes (Christinus marmoratus) use garages, sheds, roof tiles and woodpiles. They are multiplying in the southern and eastern suburbs. Sydney’s leaftail geckoes (Phyllurus platurus) like garages and brick walls. Green tree-frogs like drainpipes for their superior acoustics and toilets for their humidity. ‘In northern Australia the most significant human-made frog niche is the public toilet,’ writes Mike Tyler. ‘Almost all Litoria splendida [splendid tree-frogs] have been found in, on, or beside toilets.’ This amphibian should be called the ‘splendid toilet-frog’. In one ablution block Tyler found almost a hundred green frogs.
Animals in buildings are often unfazed by human company; the reverse is not always the case. When John Cotton moved into a hut on the Goulburn River with his wife and nine children in the 1840s, they were troubled by a long-eared rodent. ‘It is a pretty animal,’ he wrote, ‘but we are obliged to set traps for it as it commits sad havoc in the store, gnawing the bread etc.’ This was the white-footed rabbit-rat, which is now extinct. Cotton was the last naturalist in Victoria to see it alive.
Spiders also came inside in colonial times. ‘When disturbed they scramble along at a rapid rate,’ noted Louisa Meredith in 1844, ‘and are very frequent residents behind pictures or furniture against the wall, often causing terrific screams from one’s housemaid, which are somewhat alarming.’ I welcome spiders inside for the cockroaches they eat. According to Keith McKeown, writing in 1952, ‘it is not uncommon in Queensland, to find Huntsman Spiders kept by some people beneath their mosquito nets to deal with any stray mosquitoes that may happen to find their way within the defences!’
Whenever I do fauna surveys in forests I pay close heed to old sheds. Their tenants are always interesting: geckoes, snakes, frogs, native rats in the rafters. Bar-sided skinks (Elamprus martini) peer from cracks in walls, even in sheds in big cities. In forests they like rock outcrops and collapsed trees, big structures offering many crevices. Sheds fit their search criteria. Reptiles in other countries take over archaeological ruins. I’ve seen geckoes inside ancient Buddhist shrines in Burma and iguanas in Mayan temples in Mexico. Reptiles do very well from sacred architecture.
They also like the junk we discard. Looking for reptiles once while surveying a small patch of forest near Maroochydore, I lifted every log and slab of bark I saw without finding anything. But back near the car I spied a sheet of chipboard lying among weeds by the road and lifted that to find – snakes! There were four coiled together, three whip snakes and a small-eyed snake, a thrilling sight. Nearby was a sheet of three-ply, and another snake, a keelback, lay beneath it. Twenty paces on I found a piece of discarded carpet with another keelback underneath. Here were six snakes, all under junk among weeds, within two paces of the Sunshine Motorway, a highway so busy I later had to wait five minutes to cross it. This was terminally degraded habitat – weeds, tarmac, snarling traffic – but I wasn’t too surprised by what I found, knowing from long experience that reptiles love junk.
All fieldworkers know it. If you’re after snakes, don’t focus on logs, look for junk instead. Old roofing iron, fibro, slabs of concrete – snakes and lizards love this stuff. As reptile enthusiast Raymond Hoser pointed out in an article called ‘Australian Reptile Habitats – A Load of Rubbish!’ (1996): ‘Have you ever taken a good look at the habitat photos in a reptile book? Rarely is there any sign of human habitation or influence on the sites . . . And yet if you ask any Australian reptile person about good spots to find snakes and lizards, you’ll inevitably find out that many such spots are those littered with sheets of tin or other human rubbish.’
Too true. His article lists many of the Outback’s best dumps. One near Nyngan yielded a western brown snake, a curl snake, three Devis’s banded snakes, a goanna, and a retinue of smaller lizards and frogs. At the Cobar dump he scored netted dragons, bearded dragons, shinglebacks and geckoes. Cunnamulla’s tip turned up a western brown snake and a king brown snake, and Charleville’s housed a shingleback and a king brown, while the one at Charters Towers was bursting with goannas. The biggest score (in numbers) was twenty-nine snakes in one pile of tin (not at a tip) near Sydney.
Hoser can’t explain all this. ‘Perhaps one day some keen PhD student will look at reptiles and tin and solve the mystery for us,’ he suggests. ‘It’s not just tin, though. I’d hate to recall the number of reptiles I’ve found over the years sheltering under railway sleepers, cardboard boxes on the edge of bush tracks and even old tyres. If you ask me to recall all the reptiles and frogs I’ve found under man-made cover, I’d fill several books.’ So would I. Reptiles love the spaces roofing iron and fibro create. Convex logs can’t compare, especially in winter when iron captures the sun’s warmth.
Mammals, frogs, spiders and centipedes like junk too. ‘I don’t habitually frequent rubbish dumps,’ writes Mike Tyler, ‘but I have noticed amongst the flotsam and jetsam in a disused and flooded quarry [frog] spawn clumps attached to the handles of a partly submerged doll’s pram’. I’ve found tiny marsupials – dunnarts and planigales – huddled under rusty scraps of iron, and also redback spiders. One redback with eggs was nesting under an old white handbag. There are all sorts of strange things in the wilds around our cities: mattresses, stoves, bags of clothes, piles of used medical supplies. I expect to find a corpse one day, but the lure of reptiles keeps me coming back. As a teenager looking for snakes and lizards, my heart would pound at the sight of a rich cache of junk. I’m not saying I like the idea of rubbish in the bush (I don’t at all), but I’m glad something benefits. The last chapter looked seriously at sewage, and by adding junk to the equation we can see how very helpful, ecologically, our wastes can be.
Junk is even more important at sea than on land. Sunken ships, like coral reefs, offer plenty of hidey-holes, and artificial reefs, formed by scuttling rows of ships together or dumping piles of concrete in the sea, work wonders for attracting fish. Snorkelling off Moreton Island, I’ve seen coloured cardinalfish and damselfish floating over a rusted World War II dredge. Reefs of junk are employed worldwide to attract fish and crayfish. Old concrete works best. One concrete reef in the Virgin Islands was found to carry eleven times the biomass of a nearby natural reef. But reef builders can go overboard. The Queensland Government made a reef recently at Bundaberg by dumping 300 cars, 400 tram carriages, 2000 tonnes of pipes, 44 blast-furnace sections
, 53 steel pontoons, six truck chassis, a gravel dredge and more. Only in Queensland, I suspect, would a government dare do this and then say so in a public report. Biologists are still debating whether artificial reefs breed up more fish or merely lure them in from elsewhere. Probably a bit of both.
The most profound change we make to the landscape may well be the capture of water. So thirsty are we for water that Australia is now a land of dams. Huge amounts of liquid are brought to the surface, shunted around and captured in dams. Viewed from above in the late afternoon when every pool captures the setting sun, Australia can look as cratered as the face of the moon. The plains sparkle as though splattered by spots of silver. Flying over an area north of Melbourne, I counted a hundred farm dams in 10 per cent of my field of vision. Dams installed for cows and sheep, and reservoirs for our own water supplies, have incidentally created tremendous opportunities for many bird species.
Articles about Canberra’s bird life penned over the years show how water attracts birds. When ‘Birds around a homestead’ was written by Charles Barrett back in 1922, Canberra boasted no large wetlands. But Lake Burley Griffin (a dam) proved so popular that birds were arriving even while the lake was filling. Pelicans and ibises, previously very rare in the ACT, are now permanent fixtures. Blue-billed ducks, hardheads, shovellers and hoary-headed grebes (now appearing in their hundreds) were unknown in Canberra before the 1960s. The swampy eastern edge of Lake Burley Griffin, and the sewage ponds nearby, are now prime habitat in the ACT for some thirty species of bird. A grey goshawk and a little eagle flew by when I visited recently with birdwatcher Doug Laing. Birds of prey do well around artificial waters, as food (birds and rats) is always plentiful.
Coalmines need lots of water, which is used to separate the coal from rock. Dams built for the central Queensland coalfields are havens for birds. The Saraji coalfield is one of many with a spectacular wetland. Here I’ve seen swans, great crested grebes, cotton pygmy geese, and white-breasted sea eagles tending a nest in a tree. Most sea eagles in central Queensland owe their existence to coal (and to cotton, a water-hungry crop).